The documentation says : "the roll represents the device's sideway tilt between -90 and 90 degrees on the X-axis. The tilt angle is 0 degrees when the device is flat on its back, -90 degrees when the screen faces left, and 90 degrees when the screen faces right." but on my two phones (HTC magic and HTC desire), I've got positive degrees when I turn the phone toward the left side and negative toward the right.
Who's wrong ?